Add Support for ESP32 Ethernet and ESP32 Serial Devices

[sans-ltd]

Hello together,
we use ESPReader on the ESP32 POE EA (External Antenna) from Olimex. To get this working, we made the following changes:

1. Add support for Ethernet. The configuration still needs to be done with the WiFi Access Point. In our case, we remove the WiFi antenna after doing the config, so we did not disable the AP.
   To enable ethernet, add #define ESP32_ETH in config.h or via platformio.ini
2. Add support for hardware RS-232 of the ESP32.
3. Add a work around for MicroDebug to work well on the ESP32.

[mruettgers]

Thanks for this addition, I'll have a look at it in detail as soon I have the time. Right now I'm busy with my bachelor thesis at the moment and won't have time to work on SMLReader again until March.

[bulior]

Hey mruettgers,
have you had time to implement the ESP32?
I will be very glad for this

[sans-ltd]

In the meantime, you could also use our fork, where we implemented the ESP32 support:
https://github.com/sans-ltd/SMLReader
Regards
Florian